The present invention relates to an image forming apparatus such as an electrophotographic type color copying machine or a color printer, in which developed developing agent images are superposed one upon the other in succession to form a colored image.
In the general method of forming a full color image, as disclosed in Japanese Patent Unexamined Publication H/6-110343, the formation of a visible image on a photoreceptor drum by the steps of the charging, light-exposure and development with the developing and the transfer of the developed visible image onto a recording medium or an intermediate transfer medium are successively carried out for each color, and these steps of formation and transfer of the visible image for each color are carried out repeatedly depending on the number of colored developing agents used.
When a visible image of a second developing agent is transferred onto a visible image of a first developing agent formed in advance, the transfer capability of the second visible image tends to be markedly impaired by the residual charge of the first developing agent transferred in advance. The impaired transfer capability brings about serious problems. First of all, the second developing agent is unlikely to be transferred onto the first developing agent, resulting in deterioration of the transferred image quality. Particularly, a so-called "hollow" phenomenon and an increase in the waste material caused by an increase in the waste toner are brought about. When it comes to, particularly, an apparatus for performing a color reproduction by superposing a plurality of colored toners one upon the other, it is difficult to reproduce a desired color.